The present invention is in the field of electrographic printers (including copiers). More specifically this invention relates to the corona charging device used to charge the surface of a photoconductor.
In electrography, a corona charging device may be employed to charge the surface of a photoconductor. Exemplary devices are disclosed by U.S. Pat. Nos. 5,485,255 and 5,424,540. The charging device may contain one or more small diameter (eg. 0.003 inch diameter) corona wires. It is important that these wires be properly tensioned. Excessive tension can result in wire breakage, whereas insufficient tension can result in wire vibration and subsequent non-uniform charging of the photoconductor, or arcing between the corona wire and adjacent grid. However, even when the wire is tensioned to the maximum, the displacement of the wire due to vibration can be unacceptable. The wire vibration is driven primarily by the corona current and can be linear or circular polarized (even chaotic) at higher current levels. Damping elements can absorb energy and limit vibration to an acceptable level.